Accumulator-reservoir in a cooling system

ABSTRACT

An accumulator-reservoir device, used in a system circulating a liquid coolant, in which a biased pressure applying member moves to reflect changing temperature induced density of the coolant. A window and an appropriately placed temperature scale traversed by the pressure applying member provide means for visually indicating the amount of expansion volume actually in use and for simultaneously comparing such amount with an amount proper for the existing ambient temperature.

United States Patent 567,024 9/ l 896 Dunn David T. Bill;

Pritam S. Bathla, Dayton, Ohio, 785,587

Dec. 20, 1968 Feb. 2, 1971 United Aircraft Products, Inc. Dayton, Ohio a corporation of Ohio Inventors Appl. No. Filed Patented Assignee ACCUMULATOR-RESERVOIR IN A COOLING SYSTEM 9 Claims, 2 Drawing Figs.

Int. Cl F251! 45/00 Field of Search 73/344, 32; 116/1 18; 237/66; 138/26, 30, 31. 104; 73/392;

References Cited UNITED STATES PATENTS 912,502 2/ 1909 Squires 138/31 1,874,91 l 8/1932 Crosthwait 73/32-X 2,580,057 12/1951 Wilhelm (I 16/1 ISUX) 2,790,606 4/1957 Morgan et al 237/63 FOREIGN PATENTS 942,559 9/ 1948 France 237/66 Primary Examiner-Louis R. Prince Assistant Examiner-Frederick Shoon Attorney.|.'E. Beringer ABSTRACT: An accumulator-reservoir device, used in a system circulating a liquid coolant, in which a biased pressure applying member moves to reflect changing temperature induced density of the coolant. A window and an appropriately placed temperature scale traversed by the pressure applying member provide means for visually indicating the amount of expansion volume actually in use and for simultaneously comparing such amount with an'amount proper for the existing v ambient temperature.

PATENTED FEB 2mm 3,559,727

27 FIG-2 2/ I 37' INVENTORS DAVID T. HILL PRITAM S. BATHLA Ue/r ATTORNEY ACCUMULATOR-RESERVOIR IN A COOLING SYSTEM This invention relates to systems circulating and cooling at liquid coolant. and particularly to accumulator-reservoir devices therein maintaining pressure in the system and accommodating temperature induced expansion of the coolant.

Although not so limited. the invention has especial application to aircraft and like installations wherein a cooling system may require relatively frequent recharging and in which it may be subject to widely different ambient temperatures. In the charging or recharging of a system as described, it is necessary to add coolant in an amount which will insure adequate expansion space under maximum expected temperature conditions and which will insure adequate-pressurization under minimum expected temperature conditions. This amount is variable depending upon the existing ambient temperature. As a result over and under pressurization of a cooling system are possible. tending to cause damage or misoperation, or both. The need for a precisely balanced system can be minimized by building extra capacity and extra loading into the accumulator device. These are undesirable recourses from standpoints of cost and weight, and in any event the service attendant must be relatively skilled and experienced to arrive at even an approximately correct charge. Pressure gauges may be applied to or built into the system but their indications are useless meaningfully related to a temperature scale and to the existing coolant temperature.

The present invention provides means to gain a continuous indication of expansion volume actually in use in the accumulator device and simultaneously to compare such amount with an amount proper for the existing coolant temperature. Thus, in the practice of the invention a service attendant can determine at a glance whether the cooling system is properly charged. Movable pressure applying means, and a temperature scale traversed thereby, are contemplated by the invention. ln initially charging and recharging the system the attendant determines coolant temperature and adds coolant until the pressure applying means reaches a point on the temperature scale corresponding to the determined coolant temperature. The remaining expansion volume accepts and approximately corresponds to the space required for maximum expansion at maximum temperatures. At the same time the volume accepted is adequate to maintain the minimum desired pressure in the system at minimum temperature values.

It is accordingly an object of the invention to provide an accumulator-reservoir device characterized as in the foregoing, and in achieving the stated ends in a relatively simple and inexpensive manner.

Other objects and structural details of the invention will appear from the following description, when read in connection with the accompanying drawings, wherein:

FIG. 1 is a diagram of a cooling system, incorporating accumulator-reservoir means in accordance with an illustrated embodiment of the invention; and

FIG. 2 is a view in longitudinal section of the accumulatorreservoir device of FIG. 1.

Referring to the drawings, the illustrated system circulates liquid coolant for cooling purposes, as for example to cool electronic equipment in aircraft. The system circulates an appropriate liquid coolant through the electronic equipment or other heat producing source, where it absorbs generated heat. From the heat source, the coolant is directed to the cooling system where heat is rejected in a suitable heat transfer device to air, other liquid or to some other medium acting as a heat sink. The coolant is then returned to the heat source where it absorbs additional heat and is again returned for cooling, the process involving a closed flow circuit in which the pump maintains continuous circulation of the flowing coolant.

Referring to the diagrammatic illustration of FIG. 1, liquid coolant is directed to a heat source by way of a conduit and returns therefrom by way of a conduit ll. The latter extends to the suction side of a pump 12, the pressure side of which is connected by a conduit extension 11a to one side of a heat exchanger 13 Within heat exchanger 13 the coolant is brought into heat transfer relation to another, relatively cooler fluid and is continuously directed through and beyond the heat exchanger by conduit means 100 leading to and forming a part of conduit 10. The conduits lla and 100 may be suitably bridged by a line 14 constituting a bypass around heat exchanger 13. A valve 15 in the bypass opens and closes flow therethrough and may be constructed for automatic operation, as for example in response to changing temperature values of the circulating coolant.

An accumulator-reservoir l6 is placed in communication with the suction side of pump 12 by a fluid flow line 17 opening into conduit 11. The device 16 provides interior space for expansion of the coolant when increasing temperature brings about a decreasing density thereof. Also, pressure applying means within the accumulator device maintains pressure in the system. An increasing density of the coolant thus will not allow the pump suction pressure to fall below the desired value, since whatever loss of pressure occurs is compensated for by movement of the pressure applying means. An outlet connection 18 in which is a pressure relief valve 19 obviates the attainment of pressure values in the accumulator device higher than a predetermined value as set by the valve 19.

As shown in H0. 2, in its illustrative embodiment, the device 16 comprises cup shaped housing sections 2! and 22. On open. opposing ends of the respective housing sections are circular flanges 23 and 24. In assembly of the housing, the flanges are brought to a face-to-face relation and clamped together by a circumferential series of installed bolt assemblies 25. At the joint between housing sections 21 and 22 is a flexible diaphragm 26, a peripheral edge of which is received between the flanges 23 and 24 and clamped by the bolt assemblies 25. The arrangement is one positively to seal upper and lower interior portions of the device 16 from one another. An upper chamber 27 is vented by an opening 28 in the base of section 21. A lower chamber 29 serves as the pressure chamber, an opening 31 therein communicating with line 17 of the system. A similar opening (not shown) communicates with outlet connection 18.

The diaphragm 26 is flexible and is mounted over the piston and forms itself to be capable of longitudinal deflection within the device. An inverted piston element 32 is clamped to one side of the diaphragm 26 to project reversely into vented chamber 27, the clamping means including a reactant plate 33 on the other side of the diaphragm and interconnecting bolt means 34. The outer projecting end of the piston 32 is formed as an expanded portion 35 achieving an adjacent, guided relation to the interior wall of housing section 21.

The diaphragm 26 and connected parts form a pressure applying member capable of relative longitudinal motion within the device 16. A compression spring 36 is based on the closed interior end of housing section 21 and is received at its other end within piston 32 to engage the closed inner end thereof. The spring 36 applies a pressure in opposition to fluid pressure in the chamber 29. The diaphragm 25, and connected parts,

tends to assume a position in which the opposingpressures are balanced.

The housing section 21 has a vertical slot 37 therein longitudinally displaced toward the closed end of such housing section. Vertical motion of the piston 32 within device 16 causes expanded portion 35 thereof longitudinally to traverse slot 37. Such expanded portion is visible through such slot and may be painted or otherwise marked for plainer observation.

As shown in FIG. 1, on the exterior of housing section 21 to either side of slot 37, are temperature scales calibrated to indicate a selected range of temperature values,1as, in the illustrated instance, minus 50 F. to plus F. The temperature scales on both sides of the slot 37 are identical but are longitudinally offset with respect to one another. The lower set of graduations to one side of the slot are flanked by the legend MlN. representing the word minimum. The upper set of graduations on the opposite side of the slot 37 similarly are flanked by the legend MAX. representing the word maximum" The arrangement is one to define minimum and maximum tolerances. The expanded portion 35 of piston 32 serves an an indicator and may be located at or between corresponding temperature graduations on the respective scales to indicate pressurization within allowable limits.

The described temperature scales on the exterior of device 16 are selected and located with reference to variable operational factors, including changing density characteristics of the liquid coolant and the range of temperatures in which the system is expected to operate. The temperature graduations. in conjunction with indicator portion 35, provide useful indication of the amount of available accumulator volume actually in use and by their predetermined calibration designate a proper position of piston 32 at differential ambient temperatures. Thus, assuming an ambient temperature of 50 the piston 32 should be so located within device 16, as a result of opposing spring and fluid pressures, as to place indicator portion 35 at or between the minimum and maximum 50 marks on the scales. So positioned, it is known that sufficient unused volume remains in the accumulator to accommodate expansion in the coolant system up to the high limit in the range of expected temperature values. Similarly, with the piston so located, a reduction in coolant pressure down to the low limit of expected temperature values will find spring 36 still sufficiently loaded to apply pressure in chamber 29. The pressure applying member in housing 16, as represented by diaphragm 26 and associated parts, moves longitudinally in the accumulator device in response to ambient temperature changes, as these changes affect coolant density. Any given coolant temperature value should find the indicator portion 35 within minimum and maximum indications of corresponding temperature value on the indicator scales. in servicing the system a position of indicator portion 35 at scale calibrations other than those of existing coolant temperature evidence an over charged or under charged system and appropriate remedy may be taken.

In the initial charging of the system, or in recharging, coolant under pressure is admitted to the system in a suitable manner. The temperature of the coolant is previously determined, if it is known to be or may be other than the ambient temperature. The traversal of indicator portion 35 relative to slot 37 is observed, and, when it arrives at a temperature indication corresponding to existing coolant temperature, addition of the coolant is interrupted.

The arrangement is one providing for simplified servicing of the cooling system. Special skill and experience on the part of the service attendant is unnecessary. Moreover, a means for precise correlation between pressure and temperature values in the system is provided enabling the accumulator device and connected parts of the system to be made to accurately controlled capacities. Small, light weight systems are possible, in keeping with and facilitating application of the system to aircraft and like use.

Modifications in structural details of the invention are, of course, possible it being intended that the invention should be limited only as indicated in attached claims.

We claim:

1. In a system circulating a fluid coolant, a pressure applying accumulator-reservoir device communicating with the system and having an expansion volume to accommodate changes in coolant density over a predetermined range of temperature, and means visually to indicate the amount of expansion volume actually in use in said device and simultaneously to permit comparison of such amount with an amount proper for the existing coolant temperature, said means including a temperature scale calibrated in tenns to indicate a proper expansion volume at existing coolant temperatures.

2. A device according to claim I, characterized in that said device includes a movable pressure applying member, the movement of which may be visually inspected relative to said temperature scale.

3. A device according to claim I, characterized in that said device Includes a housing having an exterior temperature scale thereon and an interior movable pressure applying member therein. said housing affording means through which the position of said member relative to said scale may be viewed.

4. A device according to claim 3. characterized in that the last said means afforded by said housing includes a slot traversed by said movable member, said scale having the form of temperature graduations along side said slot.

5. A device according to claim 1, characterized in that said device includes a housing having a slot of longitudinal extent therein, the temperature scale being on the exterior of said housing along side said slot, and movable pressure applying means in said housing traversing said slot and having a portion visible through said slot in an operating range of movement said pressure applying means including a flexible member stretched across the interior of said housing and a piston attached to and movable with said flexible member, said piston affording said visible portion.

6. A device'according to claim 5, wherein said housing has opposite ends and an intermediate connecting portion, characterized in that said flexible member forms with one end of said housing a pressure chamber communicating with said system, said piston extending from said flexible member toward the opposite end of said housing and being biased to apply pressure to fluid in said pressure chamber, said slot being in said intermediate connecting portion of said housing longitudinally offset toward said opposite end.

7. A device according to claim 5, characterized in that said temperature scale includes a first series of graduations on one side of said slot and a second series of graduations corresponding to the first and relatively longitudinally offset on the other side, corresponding offset graduations representing minimum and maximum tolerances in the position of said pressure applying means.

8. In a system circulating a cooling fluid or the like having a density changing with temperature, an accumulator-reservoir device communicating with the system and having an expansion volume to accommodate changes in fluid density over a predetermined range of temperatures, the changes in fluid density effecting changes in fluid volume, a movable member in said device biased to maintain pressure on the fluid in the system and assuming differential positions in response to fluid volume increases and decreases, said device including a housi'ng affording a slot elongated in the sense of movement of said movable member through which the position of said member may be viewed, and a temperature scale on said housing calibrated with reference to movement of said member, said temperature scale including graduations on said housing along side said slot progressively increasing in temperature reading from one end toward the other end thereof corresponding in direction to the direction of movement of said member responsive to increased expansion volume, said member having an indicator portion traversing said scale, the calibrations being such that in adding fluid to the system arrival of the indicator portion of said member at a temperature indication corresponding to existing fluid temperature signals the achieving of an expansion volume sufficient to accommodate expansion at the highest temperature of the predetermined temperature range and sufficient to allow said movable member to maintain pressure in the system at the lowest temperature of the predetermined temperature range.

9. A device according to claim 8 wherein said movable member includes a diaphragm forming in one end of said housing a pressure chamber and includes further a biased piston secured to said diaphragm and extending toward the opposite end of said housing, said slot being disposed in said housing toward said opposite end thereof and traversed by the indicator portion of said member, and said calibrations being on the exterior of said housing along side said slot and being spaced apart in increments of said temperature range. 

1. In a system circulating a fluid coolant, a pressure applying accumulator-reservoir device communicating with the system and having an expansion volume to accommodate changes in coolant density over a predetermined range of temperature, and means visually to indicate the amount of expansion volume actually in use in said device and simultaneously to permit comparison of such amount with an amount proper for the existing coolant temperature, said means including a temperature scale calibrated in terms to indicate a proper expansion volume at existing coolant temperatures.
 2. A device according to claim 1, characterized in that said device includes a movable pressure applying member, the movement of which may be visually inspected relative to said temperature scale.
 3. A device according to claim 1, characterized in that said device includes a housing having an exterior temperature scale thereon and an interior movable pressure applying member therein, said housing affording means through which the position of said member relative to said scale may be viewed.
 4. A device according to claim 3, characterized in that the last said means afforded by said housing includes a slot traversed by said movable member, said scale having the form of temperature graduations along side said slot.
 5. A device according to claim 1, characterized in that said device includes a housing having a slot of longitudinal extent therein, the temperature scale being on the exterior of said housing along side said slot, and movable pressure applying means in said housing traversing said slot and having a portion visible through said slot in an operating range of movement said pressure applying means including a flexible member stretched across the interior of said housing and a piston attached to and movable with said flexible member, said piston affording said visible portion.
 6. A device according to claim 5, wherein said housing has opposite ends and an intermediate connecting portion, characterized in that said flexible member forms with one end of said housing a pressure chamber communicating with said system, said piston extending from said flexible member toward the opposite end of said housing and being biased to apply pressure to fluid in said pressure chamber, said slot being in said intermediate connecting portion of said housing longitudinally offset toward said opposite end.
 7. A device according to claim 5, characterized in that said temperature scale includes a first series of graduations on one side of said slot and a second series of graduations corresponding to the first and relatively longitudinally offset on the other side, corresponding offset graduations representing minimum and maximum tolerances in the position of said pressure applying means.
 8. In a system circulating a cooling fluid or the like having a density changing with temperature, an accumulator-reservoir device communicating with the system and having an expansion volume to accommodate changes in fluid deNsity over a predetermined range of temperatures, the changes in fluid density effecting changes in fluid volume, a movable member in said device biased to maintain pressure on the fluid in the system and assuming differential positions in response to fluid volume increases and decreases, said device including a housing affording a slot elongated in the sense of movement of said movable member through which the position of said member may be viewed, and a temperature scale on said housing calibrated with reference to movement of said member, said temperature scale including graduations on said housing along side said slot progressively increasing in temperature reading from one end toward the other end thereof corresponding in direction to the direction of movement of said member responsive to increased expansion volume, said member having an indicator portion traversing said scale, the calibrations being such that in adding fluid to the system arrival of the indicator portion of said member at a temperature indication corresponding to existing fluid temperature signals the achieving of an expansion volume sufficient to accommodate expansion at the highest temperature of the predetermined temperature range and sufficient to allow said movable member to maintain pressure in the system at the lowest temperature of the predetermined temperature range.
 9. A device according to claim 8 wherein said movable member includes a diaphragm forming in one end of said housing a pressure chamber and includes further a biased piston secured to said diaphragm and extending toward the opposite end of said housing, said slot being disposed in said housing toward said opposite end thereof and traversed by the indicator portion of said member, and said calibrations being on the exterior of said housing along side said slot and being spaced apart in increments of said temperature range. 